Low-Loss Wideband Bandpass Filters Using Semi-Distributed Unit Cells

In this paper, a realization of low-loss wideband bandpass filters utilizing a periodic structure approach is presented. The recently developed novel semi-distributed composite right-left handed unit cell is considered and adopted for the design of the proposed filters. It is shown that an appropriate balancing of the structure, i.e. selection of circuit parameters allows for achieving very broad passband. Moreover, a suspended microstrip technique is utilized to reduce total insertion loss of the circuit. The presented approach has been confirmed by realization of an exemplary low-loss wideband bandpass filter. Measured operation band is within 1.0 – 9.4 GHz with total loss ranging between 0.75 to 2 dB. The obtained results proved the applicability of the presented approach.